The environmental standards for phosphorus, boron, arsenic, fluorine ions and the like in drinking water, industrial water, industrial wastewater, sewerage-treating water and various types of environmental waters have recently been tightened from the eutrophic problem due to environmental pollutions, and demands for technologies for removing these have been raised.
Phosphorus is a causative substance of eutrophy, and the regulation has been tightened especially in closed water areas. Additionally, since phosphorus is also an element whose depletion is feared, technologies for recovering it from wastewater and reutilize it are demanded.
Although boron is an essential element for growth of plants, if it exists excessively, it is known to adversely affect growth of plants. Further for human bodies, if it is contained in drinking water, the possibility is pointed out that it affects health, especially causes health disorders such as a decrease in the reproductive function.
Arsenic is contained in wastewater of nonmetal refining industries, hot wastewater of geothermal power plants, groundwater of specific area and the like. The toxicity of arsenic has long been known, and arsenic is accumulative in living bodies and is said to develop chronic intoxication, body weight reduction, perception disorder, liver disorder, dermal deposition, skin cancer and the like.
Fluorine is much contained in wastewaters from metal refining industries, glass industries, electronic material industries and the like. The influence of fluorine on human bodies is feared, and it is known that if fluorine is ingested excessively, mottled enamel, osterosclerosis and chronic fluorine toxicosis such as thyroid disorder are caused.
The amount of emission of these hazardous substances has been increased year by year along with the development of industries, and technologies for efficiently removing these hazardous substances are demanded.
As a technology for removing various types of hazardous substances as described above, for example, a technology is known which uses an adsorbent in which a powder of an inorganic ion-adsorbing material such as a hydrous ferrite salt of zirconium or hydrous cerium oxide is carried on a polymeric material.
Patent Literature 1 describes the invention of a porous formed article containing an organic polymeric resin and an inorganic ion-adsorbing material, and states that the porous formed article adsorbs phosphorus, boron and the like. A method for manufacturing the porous formed article is additionally described.